From c892f4ca9f56563f99e0ff7b79f145bc48b80dc7 Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Fri, 8 Apr 2005 07:58:55 +0000 Subject: [PATCH] AEB, Improved descrtiption of read from /dev/urandom --- man4/random.4 | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/man4/random.4 b/man4/random.4 index e9105f554..1a02c90db 100644 --- a/man4/random.4 +++ b/man4/random.4 @@ -8,6 +8,7 @@ .\" Some changes by tytso and aeb. .\" .\" 2004-12-16, John V. Belmonte/mtk, Updated init and quit scripts +.\" 2004-04-08, AEB, Improved descrtiption of read from /dev/urandom .\" .TH RANDOM 4 2003-10-25 "Linux" "Linux Programmer's Manual" .SH NAME @@ -33,8 +34,9 @@ high quality randomness such as one-time pad or key generation. When the entropy pool is empty, reads from \fB/dev/random\fP will block until additional environmental noise is gathered. .LP -When read, \fB/dev/urandom\fP device will return as many bytes as are -requested. As a result, if there is not sufficient entropy in the +A read from the \fB/dev/urandom\fP device will not block +waiting for more entropy. +As a result, if there is not sufficient entropy in the entropy pool, the returned values are theoretically vulnerable to a cryptographic attack on the algorithms used by the driver. Knowledge of how to do this is not available in the current non-classified